MicroRNA profiling between Bacillus thuringiensis Cry1Ab-susceptible and resistant European corn borer, Ostrinia nubilalis (Hübner)

Authors: YU, TIAN - University Of Kentucky; LI, XIANGRUI - Chinese Academy Of Agricultural Sciences; Coates, Brad; ZHANG, Q - University Of Kentucky; SIEGFRIED, BLAIR - University Of Nebraska; ZHOU, XUGUO - University Of Kentucky

Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2017
Publication Date: 2/16/2018
Citation: Yu, T., Li, X., Coates, B.S., Zhang, Q., Siegfried, B.D., Zhou, X. 2018. MicroRNA profiling between Bacillus thuringiensis Cry1Ab-susceptible and resistant European corn borer, Ostrinia nubilalis (Hübner). Insect Molecular Biology. 27(3):279-294. https://doi.org/10.1111/imb.12376.
DOI: https://doi.org/10.1111/imb.12376

Interpretive Summary: Resistance within population of crop pest insects that lead to their survival on Genetically modified crop plants that express insecticidal Bt Crystaliine (Cry) toxins are a threat to sustainable agricultural production in the United States and worldwide. Despite decades of research, the causal genetic mechanisms that lead to the evolution of resistance remains elusive. An ARS researcher in Ames, Iowa in cooperation with university and international collaborators used high-throughput genome sequencing technologies to isolate and estimate the differential abundance of a class of small RNA molecules called micro-RNAs that are known to modulate the expression of genes. This study demonstrated that European corn borer that are resistant to the Bt Cry1Ab toxin show significant differences in the levels of 35 micro-RNAs, of which several were predicted to modify the expression of genes involved in immune responses, and cell growth and proliferation. These results are important to university and government researchers, as well as corporate stakeholders who are interested in understanding the evolution of insecticide resistance among insect population. These data may contribute to the body of knowledge that might prolong the durability of transgenic crops that express Bt toxins.

Technical Abstract: Transgenic maize hybrids that express insecticidal Bacillus thuringiensis (Bt) crystalline (Cry) protein toxins effectively protect against feeding damage inflicted by the insect pest the European corn borer, Ostrinia nubilalis. Field monitoring and laboratory selections have detected varying levels of O. nubilalis resistance to Cry1Ab toxin. MicroRNAs (miRNAs) are short non-coding RNAs that are involved in post-transcriptional gene regulation, but any potential roles in the evolution of Bt resistance traits remain largely unknown. A total of 277 miRNAs (248 conserved and 29 novel) were predicted from a combined set of sequenced midgut tissue-derived small RNA libraries from susceptible and Cry1Ab-resistant O. nubilalis larvae originally collected on Cry1Ab transgenic maize plants grown in Kandiyohi County, Minnesota Quantitative estimates of miRNA expression respectively predicted that 26 and 9 were respectively significantly up- and down-regulated within the Cry1Ab resistant strain. Computational predictions estimated 134,147 miRNA target sites within 3’-UTR regions of 9,059 different transcripts previously assembled within a reference O. nubilalis midgut transcriptome, and differentially-expressed miRNAs predicted to affect immune response and cell migration pathways. Putative target sites include transcripts for the candidate Bt resistance genes aminopeptidase N and cadherin. These results provide insight into the potential role of miRNAs in the evolution of Bt resistance.